I have a Yamaha CS50 that is having a problem with the keys.. they don't play individual notes, but make the same note when pushed. i was told this could be the "logic chip" ? anyone know how to diagnose/fix this prob? know where I might look for parts?

I should mention I have a second fully working yamaha cs50... but i'm hesitant to tear into it.

There are 2 large Yamaha custom chips in there, a Key assigner and a DAC. You are probably talking about one of these. It is rare for these to fail, you would be best to be looking at the circuitry around them, particularly op-amp buffers after the DAC chip.

Synthesizer service tech since 1982.Synth parts and service, Sydney Australia.

wondering... I have one beat up looking but good looking cs50, and one great looking but not working cs50(the one being discussed in this thread)...

the dilemma is what is the best economic way to go?-do I take parts from the working to make the better condition but not working one work?-do i just try and locate the prob, and have the non-working synth repaired... then sell the working but ugly one?-do i sell them both as a pair and be done with it?

i really love the synths, but times are tough and I NEED other things, and these two monsters are really luxuries if i am honest.

do you think if i took the synth and found a manual online with schematics.. a decent electronics repair person could handle the job? or do I need to go out and search for someone who specializes?

thanks!

I would make sure you goto someone who actually specializes in synths, rather than just your run of the mill "amp repair guy who works on the odd synth". And if you have the option, someone with CS-specific experience (even if more expensive) would be best... it could take someone without any CS-experience much longer to figure out the problem (costing you more money in the long-run)

p.s. it was me who suggested the potential for "logic" issues (there are many individual logic chips in one of these synths, and they seem prone to failure), but that was just based on a general (not technical) knowledge of what goes wrong on these... others will have much better knowledge of the problem based on the symptoms! good luck!